LTC3810EG LINER [Linear Technology], LTC3810EG Datasheet - Page 29

• Manufacturer Part Number: LTC3810EG
• Description: 100V Current Mode Synchronous Switching Regulator Controller
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Output Voltage Tracking
The LTC3810 allows the user to program how its output
ramps up by means of the TRACK/SS pin. Through this
pin, the output can be set up to either coincidentally or
ratiometrically track with another supply’s output, as shown
in Figure 15. In the following discussions, V
to the master LTC3810’s output and V
slave LTC3810’s output.
TRACK/SS2
V
OUT1
PIN
TO
(15a) Coincident Tracking
(16a) Coincident Tracking Setup
R3
R4
TIME
R1
R2
Figure 15. Two Different Modes of Output Voltage Tracking
Figure 16. Setup for Coincident and Ratiometric Tracking
Figure 17. Equivalent Input Circuit of Error Amplifi er
TO
V
PIN
FB1
OUT2
TRACK/SS2
V
PIN
FB2
TO
refers to the
0.8V
V
OUT1
FB2
V
V
D1
OUT1
OUT2
R3
R4
refers
V
OUT2
I
D2
To implement the coincident tracking in Figure 15a, con-
nect an additional resistive divider to V
midpoint to the TRACK/SS pin of the slave IC. The ratio of
this divider should be selected the same as that of the slave
IC’s feedback divider shown in Figure 16. In this tracking
mode, V
the ratiometric tracking, the ratio of the divider should be
exactly the same as the master IC’s feedback divider. Note
that the internal soft-start current will introduce a small
I
D3
TRACK/SS2
V
+
–
OUT1
PIN
EA2
OUT1
TO
(16b) Ratiometric Tracking Setup
(15b) Ratiometric Tracking
3810 F17
must be set higher than V
R1
R2
TO
V
PIN
FB1
TIME
V
PIN
FB2
TO
R3
R4
3810 F16
3810 F15
V
V
V
OUT2
OUT1
OUT2
OUT1
OUT2
LTC3810
and connect its
. To implement
29
3810fb